Liquid level gauge for ballast tanks



Jan. 8, 19512 Filed May 24, 1947 5 Sheets-Sheet l A S .nu u L I. L

' J/vvf/vok JOSEPH N. MATTH W5,

. Taeg Si E .nil L MM@ ASS lllIlA Jan. 8, 1952 J. N. MATTHEWS LIQUID LEVEL GAUGE FOR BALLAST TANKS 3 Sheets-Sheef, 2

Filed May 24, 1947 JOSEPH N. MATTHEWS 47M faim@ Jan. 8, 1952 J. N. MATTHEWS LIQUID LEVEL` GAUGE FOR BALLAST TANKS Filed May 24, 1947 Patented Jan. 8, 1952 UNETED STA'ES QVENT OFFICE.

LIQUID LEVEL GAUGE FOR BALLAST TANKS Joseph N. Matthews, Lakewood, Ohio Application May 24, 1947, Serial No. 750,328

(Cl. 'i3-302) 2 Claims.

This invention relates 'to a ship or boat, more particularly apparatus incorporated therein for determining the ballast therein, whereby the boat draft may be changed or regulated dependent on external conditions, the boat load or location of the latter, that is, where (a) the ship is being propelled without a load, fully loaded or partially loaded and/or (b) the ships load is not properly distributed and/or (c) the body of water, through which the ship is being propelled, is calm or in varying degrees of roughness. Likewise, the ship must be trimmed to avoid engagement with equipment on wharves or piers when tying thereto or being shifted therealong. To insure eiiicient propulsion under these conditions it is necessary to ascertain the depth of the water in each tank or certain of the tanks, so as to determine which tanks should be supplied with additional water, the volume therein or other tanks reduced, or all of the Water in the tanks withdrawn therefrom. Other conditions arise where it is highly important to quickly determine the depth of Water in the tanks--certain tanks or all thereof; for example, when all or substantially all of the water is to be withdrawn, inwhich event the pumps must be slowed down in time to prevent the latter from pumping air, instead of Water, from the tanks. Each ship, when designed has a certain cargo carrying capacity and a certain capacity for ballast, the

latter to be increased or decreased as conditions require by supplying water to one or more of the ballast tanks or discharging water therefrom. Once the ballast tanks are filled, the required ballast regulation and-or draft of the ship to meet the operating conditions above referred to at any time can be determined by measuring the hydrostatic head in one or more of the tanks. My invention has been applied to a ship or boat of the ore carrying type. On ships of this type, so` far as my knowledge goes, it is customary for a seaman to stand on the ships deck and project a rod into the Water in each tank (or in one or more tanks according to his orders) to measure the depth of the Water therein by the water line on the rod. Aside from the fact that .these operations involve an undue amount of labor and time, it is often a dangerous physical operation, due to the weather or sea conditions, and

during a precipitationtherod may get wet from the rain and hence prevent a correct reading of the water line on the rod. These disadvantages in measuring the depth of watervin the ships tanks are more apparent wherethe ship orboat is large in size, some of which are approximately 600 feet along and contain as many as 18 tanks (9 tanks at each side of the ship holds). My invention eliminates the disadvantages above referred to on the one hand and on the other hand provides for readily taking static-head readings in each of the tanks or any selected tanks, as desired, at one or more stations, in a short period of time, whereby the trim of the ship may be quickly regulated or changed.

One object of the invention is to provide in a ship or boat equipped with water holding tanks, improved means for selectively measuring the depth of water in the tanks as a means of determining Whether Water is to be supplied to or discharged from one or more of the tanks to regulate the ships draft dependent upon or to meet various operation conditions.

Another object of the invention is to provide in a ship or boat equipped with water holding ballast tanks, improved means for determining at one or more stations the depth of water in each tank in a simplied manner and in a relatively short period or" time.

Another object of the invention is to provide in a ship or boat equipped with Water holding ballast tanks, improved Water depth determing means employing a single gage at an operating- Other objects of the invention Will be ap-v parent to those skilled in the art to which my invention relates from the following description Vtaken in connection with the accompanying drawings, wherein Fig. l is a view, partly in side elevation and partly in section on the line I--l of Fig. 2, -of

Aa boat equipped with apparatus embodying my invention.

Fig. 2 is a section on the line 2 -2 of Fig. 1, enlarged.

Fig. 3 'is a longitudinal section through the valve, substantially on the line 3-3 of Fig. 4.

Fig. 4 is a plan view of the valve. Fig. 5 is a diagrammatic view, the valve being in section on the line` 5-5 of Fig. 3.

Fig. 6 is a diagrammatic view showing the system for indicating the depth of the water in the respective tanks at a remote location.

Fig. 7 illustrates a modified form of gage.

Fig. 7a is a fragmentary section through the valve for the by-pass pipe.

Fig. 7b is a fragmentary side elevation of the check valve for the by-pass, parts being broken away.

Fig. 8 is a diagrammatic view showing a modied form.

Fig. 9 is a fragmentary side view (parts being broken away) of one of the valves shown in Fig. 8.

Fig. 9a is a plan view of the valve shown in Fig. 9, parts being broken away.

In the drawings, A indicates as an entirety a boat of the ore carrying type, which is chosen to exemplify the application of my invention, constructed to provide (a) holds B between the bow and super-structure (pilot house and offlcers quarters) C and the stern D containing the engine room d and (b) tanks along the port and Starboard sides of the boat, outwardly of the nolds B, the tanks on the port side being designated I, 2, 3, il, and 6 and those on the starboard side being designated I', 2', 3', 4', 5 and 6. It will b-e understood that the number of tanks on each side of the boat A will depend on its length and other factors. Each tank is provided for by the outer side wall a of the hull, the side and bottom walls b of the adjacent hold B, the bottom wall a of the hull, a partition b disposed centrally of the hull between the bottom wall b and bottom wall a', and a top wall c, which provides a space E-between it and the deck F, for a purpose later set forth. Each wall c is formed with a suitable vent leading into the space E to permit escape and intake of air due to filling and emptying of the adjacent tank and discharge of air supplied to the tank in ascertaini ing the depth of water therein as hereinafter described. G indicates pipes extending through and supported on the reinforcing plates g between the bottom walls a and b, these pipes being connected to one or more pumps (not shown) the operation of which serves to supply water therethrough to the tanks and draw water therefrom in maintaining or changing the draft of the boat. In the application of the invention above referred to the top walls of the tanks would be approximately 231/2 feet above the hull bottom wall a and provide a water depth, when the tanks are filled to the maximum level, of approximately 22 feet, so as to leave a space above the water level therein.

'I indicates a pipe depending vertically` into each tank and terminating a short distance (preferably approximately three inches) above the bottom wall a. The lower or free end of each pipe 'I is open, so that the water in the adjacent tank rises and falls in the pipe corresponding to the level in the tank incident to the supply of water to the tank or withdrawal of water therefrom. The upper end of each pipe 'I is connected to one end of a pipe ia preferably leading through the adjacent space E and connected at its opposite end to a port 8 formed in the casing 8a of a master valve which is located at an operating station, such as the engine room d. As will be understood from Fig'. 5, the valve casing 8a is formed with a plurality of ports 8, corresponding to the number of tanks, each pipe In the solenoid operated type.

being connected to one of these ports. By prefer-- ence, as shown in Fig. 1, intermediate portions of the pipes la.' (except the pipes related to tanks 6 and 6') between the tanks and Valve S are extended upwardly, as shown at 1', to permit gravitation of condensation of moisture in the pipes. In this arrangement condensation in one portion of each pipe 7a drains back into the adjacent pipe 'i and condensation in the other portion drains into a collector 7b, preferably consisting of a U-section (one only being shown) interposed in the pipe Ia in close relation to and at a level below the valve 9. The bottom portion of the U -section 'ib is provided with a discharge opening which is sealed closed by a screw plug.

The inner wall of the valve causing 8a is of conical shape to form a seat for the valve element Iii having at one side a device (preferably a wheel) Illa for turning it and at its opposite end a shank Ib. The outer end portion of the shank Ib is provided with screw threads to take a nut II. The nut II serves as an abutment for the outer end of a spring I Ia coiled around the shank Ifib; the inner end of the spring IIa engages an annular plate I2 seated on the vaive casing 8a. In this arrangement the spring IIa cooperates with the nut I I and plate I2 to yieldably maintain the valve element IB in its seat in the casing 8a. The side wall of the valve element IG is formed with an annular recess I3 which registers with the inner end of an inlet port I3a formed in the valve casing 8a. The outer end of the port ISa is connected to a conduit I4, to which a uid in the gaseous phase (preferably air) under pressure is supplied from a reservoir Ita, as later set forth. At one side of the recess I3, the valve element is formed with alduct I5 having a vertical portion connected with the recess I3 and an outwardly extending portion arranged to register with each of the ports 8, whereby by rotation of the Valve element I, air under pressure is supplied from the conduit I4 to each of the ports 8 according to the angular position-of the valve element. As the valve element I is provided with only one duct I5, all of the ports 3 are closed when the valve element is in neutral position (see Fig. 5) and when the valve element is rotated to connect the duct I5 with any one of the ports 8 all lof the remaining ports are closed. The air under pressure may be supplied to the reservoir Illa from any suitable source; that is, a compressor on board the boat and forming part of its equipment and connected to the reservoir Illa or from a suitable pump I'I connected to the reservoir and driven by a suitable motor Ila (the pump and motor being shown diagrammatically) The air in the reservoir Ilia is preferably maintained at approximately 25 pounds pressure. Ad-

jacent the valve 9 each pipe 'la is provided with a cut-o ff lx, each thereof being adapted to be closed when repairs are needed.A

The air connections between the reservoir I4a and the pipe I4 on the inlet side of the valve I4b consist of the following: leading from the reservoir Ida to the pipe I4 and provided adjacent the reservoir with an adjustable constant pressure valve I9. Outwardly of the valve I9 is an adjustable valve 2() for regulating the flow of air through the pipe I4:1:. |80 indicates a cut-off in the pipe I4x preferably of The cut-off IDU is normally closed under spring pressure, but operable by a suitable push button IOa for' closing a circuit Ib therefor, whereby, upon closing of the circuit, the coil of the solenoid is energized to open the valve IDU. I 0I indicates a by-pass connected to the pipe I at opposite sides of the valve Ion, as shown at Ila, IIb. |02 indicates Ida: indicates a pipe assurer an adjustable check valve, preferably comprising a sight feed device (commonly referred to as sight feed bubbler) and consisting of a support having a depending transparent receptacle l02a '(see Fig. 7b) containing a body of water and air inlet 'and outlet connections interposed in the by-pa'ss IGI, the inlet being connected to a downwaidly extending pipe the lower end of which leads into the water below its level and provided with an adjustable needle valve, whereby the flow of airthrough the device may be regulated. The needle valve of the device |02 is adjusted to permlt'a slight, substantially zero flow of air to the pipe 14x to maintain the latter filled therewith. |03, vHl3a, indicate strainers preferably provided in-the pipe Ha: inwardly of the valve IBO and at opposite sides of the adjacent connection Illia of the by-pass lill therewith and Id indicates a Strainer in the by-pass It! between the sight feed device 102 and the connection Ulla of the bypass HH with the pipe leas. Each strainer serves to sift out any dirt or solid particles existing in the air; and each is provided with a removable plug to permit cleaning of the strainer. |95 indica't'es apipe connected to the pipe Mr between A the valve I4b and the connection lil lb of the bypass IUI with the pipe 44m. IBB indicates a suitable gage connected to the pipe IE5 for registering the water depth in each selected tank in the manner later setforth, the air pipe connection betwen the pipe |05 and the gage being provided with a valve "36a, which may be of the relief type to avoid damage to the gage ISG. It is to be noted that flow of air under pressure through the system sets up a certain amount of friction, which increases with the length of the pipe and varies according to the depth of the water in the tanks and this frictional reaction affects the operation of the gage so that the latter does not give an accurate reading. To insure proper and quick operation of the gage, I provide the by-pass IUI with the air supply device m2 therein, to maintain air in the pipe |43: outwardly of the cut-off |00 and in the pipe H35, so that when the cut-off Ille is operated to admit air under pressure; friction which would otherwise result from a constant iiow of the air and affect the operation of the gage is eliminated.

l01 indicates an auxiliary by-pass between the reservoir Ma and pipe ltr, outwardly of the pipe 105,the connection of the by-pass |91 with the pipe l4'consisting of a three-way rotary valve lilla, which in normal position connects the pipe |42: with the pipe I4, as shown in Fig. 7a. lllindicates a cut-off in the auxiliary by-pass |01 preferably of the solenoid operated type. The cut-off |08 is normally closed under spring pressure, but is operable by a suitable push button Illa for closing a circuit Ib therefor, whereby, upon closing of the circuit, the coil of thc solenoid is energized to open the cut-off IDS. The auxiliary'by-pass IGT is employed to supply air under pressure through pipe l #i and the pipes 'la and 1 for each tank, so as to remove moisture, condensation therein and water which may have been forced into the latter pipes from the ballast tanks due to heavy we ather conditions. Such removal may be found desirablel when readings of the water depths are tobe made, but more particularly in the fall and winter before the boat is put out'of service for the winter, so that the pipes and connections will be dry and danger of freezing eliminated. As. will be observed, when moisture and/or water inthe pipes 1a, 1, are to be removed, the valve lia is operated to 6. close pipe Ms and connect the lay-pass i01- with the pipe I4 and the valve 9 is operated to con-" neet the pipe lIll with each of the pipes 'la Aand when each connection is made the cut-off AH'I8`is operated as above set forth. m9 indicates a suitable safety valve lmounted on the top Wall ofthe reservoir Ma.

Current for the circuits |001) and 'H3817 may be supplied from a. suitabie battery' (not shown) or' the battery hereinafter referred to.

As will be understood, the pipe in each ballast tank provides a column of water 'substantially equal in depth to that in the adjacent tankl a't all timesl (except as hereinafter set forth), so that by displacing the water in the pipe by the application thereto of air under pressure, the pressure, which is required for Such displace; ment, as indicated on the gage, will equal the static-headA of the volume of Water in the pipe and this pressure in turn,- in connection with the computations later referred to, is utilized to indicate the depth of the water in the tank. Ar.- cordingly, by rotation of the valve element I0 to effect communication between the reservoir Ma and the pipe "I in each tank or any selected tank, the depth of the water therein may be deter-v mined. The gage |06 may be graduated to in'- dicate the volume of water in each tank, the hyY` drostatic-head of the water or its depth. -By preference, the gage ISB is graduated to indicate the Adepth of the water in the pipe measured in feet and inches.

The gage [OES shown in Fig. 5 is of the grad'-V uated dial type, but other forms of 'gages may be employed, such as a manometer shown in Fig. 7.

Operation- As already set forth, cut-offs itil and |58 are closed, valve l'la is in normal posietion connecting the pipe Mx with the inlet pipe I4 and cutting of by-pass IH?, valve I b isI open and valve S is in normal position (see Fig. 5) closing all ports 8 for the pipes la. When the depth of water in any selected tank is to be determined,- the valve 9 is operated to connect the latter with the pipe 'la leading to the selected tank; next; the push button mila is operated to open valve |00 which supplies air under pressure from the constant pressure valve 'i9 to pipe i4, valve 9,

pipe la and pipe 'I of the selected tank, the e' fect of which is to displace the water in the pipe 1, the pressure required for such displacement being indicated on the `gage 586-. which being graduated i-n feet and inches, exhibits thef depth of the water in the selected tank. The depth of the water in any number or all of the tanks may and pipe A'I'of the selected tank, the result being -tank. If a more accurate determination of the water depths in the tanks is required the lineal dimension between the bottom ci the tanks ansi lower ends of the pipes must be added to the reciprocatable in a cylinder 26a.

indications shown by the gage of the hand or the latter pre-adjusted relative to its zero position.

As will be apparent, these readings will enable the commanding oiicer to order water to be supplied to or withdrawn from the tank or tanks of which a depth reading was made.

It will be observed that when a depth reading of each tank isvmade and the valve 9 is operated to neutral position or to another operating position, the pipe `Ia and adjacent pipe I remain charged with air, so that in operating the valve 9 to make a subsequent reading of the water depth in each tank the time required for the supplied air und-er pressure to ow to the adjacent pipe 'I and displace the water therein and friction are eliminated. It will thus be seen that the valve 9 may be readily rotated from one operating position to another operating position and all of the pipe readings quickly made. If prior to a subsequent reading of a tank water has been supplied thereto, the static-head resulting from such supply will cause a rise of the water in the adjacent pipe I and compression of the air therein; and upon making the subsequent reading the supplied air pressure, in addition to the pressure in the pipe previously utilized to displace the water therein, Will be indicated on the gage by movement of the gage arm to a higher point or graduation. If prior to a subsequent depth reading of a pipe a portion of the water in the adjacent tank has been withdrawn therefrom, the reduced static-head in the tank will permit escape of air from the adjacent pipe l to equalize its pressure and the then existing static-head, but upon making the subsequent reading the applied air pressure corresponding to the static-head of the water in the pipe will be indicated by the gage |56.

'Ix' indicates a supplemental cut-oi provided in each pipe ia in close relation to the adjacent i tank, whereby air flow to the latter may be cut off when the tank is to be inspected or its Walls repaired.

Means, indicated as an entirety at 22, are provided for simultaneously indicating at a control station (for example-the pilot house), remote from the operating station, the reading for each tank each time a depth reading is made. The means 22 herein shown is of the electrical type and consists of the following: 23 indicates a casing mounted on the wall of the engine room.- The casing encloses an arc shaped resistance 23a one end of which is connected to a lead 23D, the lead in turn being connected to the positive side of a suitable battery 24, having its negative side grounded at 24a. The walls of the casing'23 support a shaft carrying an arm 25 arranged to engage the resistance 23a and movable from end to end thereof. The shaft for the arm 25 has xed to it a gear 25a engaged by a ratchet 25D, the

lower end of which is provided with a piston 26 As shown in Fig. 5, the cylinder 26a is connected to the conduit H35, so that when the valve 9 is operated to measure the dep h of the water in each of the pipes 'I the pressure operates the gage ISE .and

simultaneously forces the piston 26 upwardly,

whereby the arm 25 is revolved relative to the resistance 23a. A spring 2 is interposed between the end wall of thecylinder 25a and piston 26 and normally operates to bias the 'latter downwardly to swing the arm 25 to 'zero position as shown in Fig. 6. A stop may be provided to limit the movement of the arm 25, under influence of the spring 2T, at the zero position. The arm 25 is connected through a lead 28 to one side or a suitable electrically operated gage 29 having a scale 29a graduated similarly to the scale for the gage IUE. The opposite side of the gage 29 is grounded at 29h. The resistance 23a is constructed to control the current to the gage 29, so that in each operation of the valve 9 the arm 25h' thereof swings relative to the scale 25a. a distance equal to the movement of the arm for the gage H15. 38 indicates a panel associated with the gage 29 and mounting a series of lamps 3 one lamp for each ballast tank, one side of the lamps being grounded at 3Ia. The other sides of the lamps 3l are connected by leads 32 (one for each lamp) to contacts 32a, respectively, mounted on an annular collar 33 (see Fig. 3) formed of insulating material and suitably x'ed to the inner end of the valve casing`8a. The outer end of the shank Ib for the valve element I is provided with an arm 33a connected by a lead 311 with the battery 24, the arm being suitably insulated rom the shank Ib. The outer end of the arm 33a is arranged to engage the contacts 32a. when the valve element IS is rotated. The arm 33a is xed to the shank Ib in alinement with the duct I5 and the contacts 32a. are alined with the ports 8, respectively, whereby operation of the wheel Ia to supply air pressure to each of the pipes 'i will insure closing of the circuit for the lamp corresponding to the tank in which each pipe is mounted. In operation, assuming that the depth of tank 4 is to be determined, the valve element I0 is turned counter-clockwise, as viewed in Fig. 4 (clockwise as viewed in Fig. 6i from neutral position until duct I5 registers with the port 3 related to pipe 7a, which is connected to the pipe 'I of ballast tank t; in this movement of the valve element I, the arm 33a sweeps over the contacts related to the lamps corresponding to tanks I, 2 and 3, momentarily lighting these lamps and comes to rest on the contact related to the lamp correspending to tank Il, which lamp remains lighted while 'the depth of tank 4 is determined and notifies the officer in the pilot house which tank is being tested, whereas the gage 29 exhibits in lineal dimensions thestatic-head in pipe l of the tank, whereby the depth of water in the latter can be determined as already set forth.

The operating device lila. is preferably provided with an arrow 35 in alined relation to the duct i5. The arrow 35 serves as a guide for the operative to indicate the position of the duct I5 when the device Ia is being operated.

Fig. 8 illustrates anY apparatus for making depth readings at any one of a plurality of operating stations, two stations H, I, being shown for exemplii'lcation, the valves for the several ballast tanks being selectively controlled at each station by a main switch and a selector or master switch and the main switch of each station being interconnected to the main switch of the other station or stations so that when a depth reading or readings are being made at one station, the main switches of the remaining stations are automatically inoperative.

Referring toFlgs. 8, 9 and 9a., Im, 21;, 39:, indicate water holding tanks on the port side of the boat and Isc', 2r', 3x', Water holding tanks on the starboard s ide of the boat. These respective tanks are provided for as shown in Fig. 2 and the number at each side of the boat will depend on the length thereof and other factors. I'It indicates a motor, which is mounted on a support I I I and through a main switch II la at station H or main switch IIIa: at station I and leads IIIa, is

supplied with current from a suitable battery |||b and drives a suitable compressor 2 for supplying compressed air to a reservoir |2a having a relief valve |2b.

Each main switch l I la, I| Ix, consists of a plurality of terminals and moving contact carrying arms connected together and movable to engage the adjacent terminals to connect in the battery |||b -for all of the circuits for the adjacent station. ||3 is a discharge pipe leading from the reservoir ||2a and connected at its outer end to pipes |3a each common to the tanks at one side of the boat and having branches ||3b, one for each adjacent tank terminating in a pipe ||3c which extends downwardly in the tank to within a predetermined distance of the bottom of the latter, preferably approximately three inches therefrom. I|2c indicates an adjustable constant pressure valve in the pipe ||3, preferably disposed adjacent to the reservoir I |2a. l e indicates a cut-off in the. pipe ||3 outwardly of the valve |20, the cut-off being normally closed by a spring ||4a (see Figs. 9 and 9a) and opened by a solenoid Hflb, the coil of which is connected by leads I |40, I I la', through each main switch with the battery IIIb, the circuit to the coil of the solenoid being completed subject to operation of a switch IIt when either main switch IIIa, IIIsc, is closed.

Each of the circuits I Mc, which control the operation of the solenoid |I4b, is provided with a switch Har, preferably of the push-button type, and operated in the manner later set forth. The pipe |33 is preferably provided at opposite sides of the cut-off Ilfl with strainers I|5 to collect dirt and other foreign matter which may exist in the supplied air. I l5 indicates a by-pass for air connected to the pipe I |3 inwardly of the inner strainer ||5 and outwardly of the outer strainer H5 and provided with an adjustable check valve, preferably a sight feed ldevice il? arranged to provide a minimum supply of air in the pipes IISa, ||3b, and the pipe H3 outwardly of the cut-off ||4 to reduce or eliminate friction incident to air flow as already se* forth. The device lil is similar in construction to the sight feed device shown in Fig. 5. I I3 indicates strainers preferably disposed in the by-pass H5 at opposite sides of the sight feed device Hl' to collect dust and other foreign matter existing in the air. ||9 indicates auxiliary branch pip-es connected to the system outwardly ,of the oy-pass I I5, for example, one of the pipes lla, and connected at their outer ends to gages ||9a ass-oeiated with the stations H, I, respectively. The

such as shown in Fig. '7.

|22 indicates a cut-olf in each branch pipe `when the circuit to the coil thereof 4is closed.

In Fig. 8, only one cut-off |28 is shown provided with a spring, so that the other cut-offs and associated parts will be more clearly shown.

I2I indicates suitable strainers disposed in each as viewed in Fig. 8).

branch piper||3b at opposite sides of the adiacent cut-ofi |20 to collect dirt and other foreign matter existing in the air. |22, |22rc, indicate selector or master switches, associated with the stations H, I, respectively. Each of the switches |22, |22x, consists of a' support provided with terminals, one for each tank Ix, 2r, 3x, 2:c' 3x', and a revoluble hand having a contact arranged to engage each of the adjacent terminals upon movement of the hand about its axis, so as tov close the circuit through that terminal corresponding to the tank selected at any time to be tested for water depth. As will later be apparent, the operation of the master switch |22 is effective when the main switch I I la is closed and the master switch |22m is effective when the main switch I I I :c is closed.

For station H, the circuit for the solenoid coil for each cut-olf |20 is traced as follows: one end of coil, lead |23, lead |23a, terminal of the master switch |22 corresponding to the tank to be tested, master switch hand, lead |24, lead |24a, lead |24b to main switch terminal, switch arm lead |25 to battery; battery, lead |25, main switch arm :c3 and lead |21 to the opposite end of solenoid coil.

For station I, the circuit for the solenoid coil for each cut-olf |20 is traced as follows: one end of coil, lead |23, lead |23, terminal of the master switch |2231 corresponding to the tank to be tested, master switch hand, lead |29, lead |29a to terminal of main switch I l Ix, main switch arm e, lead |35, lead |3511 to battery; battery, lead |3|, main switch arm z' and lead |32 to the opposite end of solenoid coil.

The main switches |IIa, Hlm, are normally maintained in circuit open position so that each may be operated, independently of the other, and manually operated to closed position by a suitable lever or handle (not shown).

Means, indicated as an entirety at |33, are provided to interconnect the main switches, so that when one thereof is operated to closed position, the other main switch is (a) held in an inoperative or open position, or (b) if in closed position it is automatically moved to open position, to preclude the operation of depth readings at the station adjacent to the latter switch. The inter-connecting means |33 consist of solenoids |34, I341:, associated with the Vmain switches I a, respectively, and circuits therefor, the current flow for each solenoid coil, in the arrangement shown, being in a direction to move its core -outwardly and resist inward movement thereof. Each core of the solenoids is operatively connected to the movable arms of the adjacent main switch and controlled by the closing of the other main switch; that is, the coil of the solenoid related to one switch is energized, to control its core, upon the closing of a circuit by the closing of the other switch. For example, with both main switches Ia, I Im, open, as shown in Fig. 8, and it is desired to take tank readings at station H, main switch IIIaI is moved to closed position, which operation closes the circuit |35 for the coil of -solenoid |34, which coil being energized, will prevent movement of its core inwardly (toward the right as viewed in Fig. 8) if it is de- Vsied to take tank readingsat station I, main switch |:c is moved to closed position, which operation closes the circuit |35 for the coil of solenoid |34, which coil being energized, will prevent movement of its core inwardly (toward the left The circuit |35 is traced as follows: from one end of coil of solenoid |3466, lead |33, lead |241) to terminal of main switch IIla, switch arm lead-|25 to battery; battery,-

lead 25, switch arm rc2, lead |37 and lead |38 to the opposite end of the coil. The circuit |35:v is' traced as follows: from one end of coilof solenoid |4| indicates an electric bulb parallelly connected in the circuit |351: and mounted adjacent the main switch la to serve as a signal to show that the main switch Illa: is closed and in operation. |4 indicates an electric bulb parallelly connected in the circuit |35 and mounted adjacent the main switch I la: to serve as a signal to show that the main switch |||a is closed and in operation.

If the operative at either station is of the opinion that the main switch at the other station, through an oversight or otherwise, has been left closed, operation of his main switch will, through the solenoid at the other station, automatically open the switch for that station and thus disconnect the circuits thereat.

|42 indicates an electric bulb associated with the manometer H90, at station H and supplied with current by leads |24a, |2b, lead |420, and lead |31. |43 indicates an electric bulb associated with the :nanometer lisa at station I and supplied with current by lead |29a and lead MD. As each bulb |42, |43, is lighted when the adjacent main switch is closed, it serves as a signal or warning to the operative when completing a test or tests to open the main switch and stop the motor |0 and de-energize the coil of the solenoid for cut-off of the tank last tested, unless the hand of the adjacent master switch has been moved to zero position.

From the foregoing description it will be apparent that the depth readings may not only be made at any one' of several operating stations remote from the ballast tanks, but that the electrically operated devices and the circuits therefor are mounted outside of the tanks, so that contact of the water in the latter and chemicals and oils in the water cannot take place.

Operation-As already set forth, the cut-oii H4 is closed and each cut-od' |20 is closed and main switches are open (but one may be in closed position) and switches 14x are open. If reading is to be taken at one station-for example, at station H-of water depth in tank 3x on the port side of boat, the hand of master switch |22 is swung clockwise into engagement with terminal 3; next, the main switch a is operated to close the circuit |||a, which (a) operates the motor H0 to drive the compressor ||2 and build up pressure in the reservoir |2a and (b) energizes coil of solenoid I34 to make main switch Illa: inoperative, and circuit for the cut-oit |20 in branch pipe ||3b leading to tank 3.7:, to open cut-oit |28: next, the adjacent push but/ton H41: is operated and held in closed position for approximately two secondsto open cut-oit H4 and f supply air under pressure through pipes i3, |1311, N3D, leading to tank 3:1: an`d the pipe H30,

'to displace the water in the latter, the pressure to effect such displacement being indicated on the adjacent gage |9a. As these pipes are filled with air, a reading on the gage is quickly made.

As the cut-off i i4 is open only when push button H43: is operated, it will be observed that when one reading is made, the hand of the gage |22 may be moved into engagement with .another are purely illustrative and are not intendedl to be in any sense limiting.

What I claim is:

1. In a system for determining at an operating station the liquid levels in the ballast tanks of a ship consisting of a plurality of pipes, each depending vertically into one of the tanks and terminating at a position adjacent the bottom thereof, each said pipe having an unobstructed lower open end to permit intake of liquid into said pipe and discharge of liquid therefrom, a source of supply of a gaseous medium under pressure, gaseous medium supply connections between said source of supply and said depending pipes consisting of a main conduit leading from said source of supply and branch conduits con'- nected to and leading from said main conduit to the upper ends of said depending pipes, respectively, a pressure regulating valve in said main conduit, a gage having connection with said main conduit outwardly of said valve, and a valve mechanism in said connections outwardly of the connection of said gage with said main conduit and arranged to selectively supply the gaseous medium to each depending pipe to displace all of the liquid therein, and indicate the pressure on said ,gage` a separate conduit provided between said source of supply of gaseous medium and said main conduit to by-pass said regulating valve, the connection of said separate conduit to said main conduit consisting of a valve arranged to simultaneously close off the supply of said medium through said main conduit and connect said separate conduit thereto, whereby upon operation of said valve mechanism the gaseous medium may be supplied direct from said source of supply to each of said branch conduits to displace sediment and foreign matter accumulated therein.

2. In a system for determining at a selected one of a plurality of operating stations the liquid leveis in the ballast tanks of a ship consisting of a source of supply of gaseous medium under pressure, a main discharge conduit leading from said source of gaseous medium supply, branch discharge pipes connected to said main discharge pipe, the terminating end portion of each branch pipe being vertically disposed in and depending into one of the tanks to a point adjacent the bottom thereof and having an unobstructed open end adapted to receive liquid supplied to the tank, a normally closed electrically operated valve in said main discharge conduit, a separate normally clcsedelectrically operated valve in each of said branch pipes, circuits for said electricallyA operated valves adapted to be connected to a source of current supply, a switch mechanism at each station in the circuits for said valves in said branch pipes for selectively operating said valves to open position, a separate switch at each station in the circuit for the valve in said main discharge conduit for opening it, the opening of said valve in said main discharge conduit and the valve for any selected one cf said branch conduits serving to displace all of the liquid in the adjacent depending pipe, a gage at each station in said main discharge conduit between Said source of supply of gaseous medium and the valves for said branch conduits, said gage, after displacement of the liquid in the depending pipe for the selected branch conduit and upon closing of the valve in said main discharge conduit, being arranged to register the pressure in said depending pipe, an auxiliary switch at each station in the circuits for the adjacent selective switch 13 mechanism and said separate switch, a relay at each station operatively connected to the adjacent auxiliary switch, and a circuit for each relay adapted to be controlled by the auxiliary switch at the remote station, the operation of either auxiliary switch to closed position` being arranged to close the circuit for the coil of the relay connected to the other auxiliary switch to prevent closing of the latter.

JOSEPH N. MATTHEWS.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 31,125 Nystrom Jan. 15, 1861 656,947 Cowles Aug. 28, 1900 Number Number Name Date Wheeler Nov. 14, 1905 Ford Jan. 13, 1914 Dexter June 23, 1914 Walton Feb. 22, 1916 Staud Mar. 9, 1920 Star Mar. 7, 1933 Conley Sept. 3, 1940 Hebeler Sept. 11, 1945 Eby May 24, 1949 FOREIGN PATENTS Country Date Germany Apr. 3, 1918 Austria Aug. l1, 1930 Great Britain Nov. 4, 1935 

